Beet J. Stag is Masato's Buddyroid that takes the form of a Japanese rhinoceros beetle/stag beetle-type android. He often simply referred to as 'J,' his middle initial stands for both "Justice" and Jueki. Created in subspace by Masato, J is sent to reality by stowing away in a Vaglass Megazord that Enter transported. Like Masato, J is an egotist who likes appearing cool. However, he is more extreme in a sense that he shows little to no interest in anything that does not concern him. He has a habit of always standing in the way of people, typically Masato, which annoys whoever he inconveniences. Unlike other Buddyroids, J is battle-ready and is outfitted with a Marker System that allows him to recreate Masato's avatar if destroyed and activate the duo's personal Buster Machines. Because of this, J is Masato's anchor to the real world. He is Masato's partner both in and out of combat, with the ability to transform into the Stag Buster. This process sheds off much of J's outer armor, which either becomes parts of Beet Buster's suit (when transforming together) or is simply cast off and converted into data (when transforming on his own). As a result, Masato is unable to become Beet Buster without J. Copies of these armor pieces can also be transferred to allow Masato to transform without J doing so as well.